/**
 * @file sequential_file_reader.h
 * @author ERaftGroup
 * @brief
 * @version 0.1
 * @date 2023-08-30
 *
 * @copyright Copyright (c) 2023
 *
 */

// MIT License

// Copyright (c) 2019 Isac Casapu

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#pragma once

#include <cstdint>
#include <functional>
#include <memory>
#include <string>

// SequentialFileReader: Read a file using using mmap(). Attempt to overlap
// reads of the file and writes by the user's code by reading the next segment

class SequentialFileReader {
 public:
  SequentialFileReader(SequentialFileReader&&);
  SequentialFileReader& operator=(SequentialFileReader&&);
  ~SequentialFileReader();

  // TODO: Provide some way to log non-critical errors which don't prevent the
  // actual reading of data, but could hurt performance

  // Read the file, calling OnChunkAvailable() whenever data are available. It
  // blocks until the reading is complete.
  void Read(size_t max_chunk_size);

  std::string GetFilePath() const {
    return m_file_path;
  }

 protected:
  // Constructor. Attempts to open the file, and throws std::system_error if it
  // fails to do so.
  SequentialFileReader(const std::string& file_name);

  // TODO: Also provide a constructor that doesn't open the file, and a separate
  // Open method.

  // OnChunkAvailable: The user needs to override this function to get called
  // when data become available.
  virtual void OnChunkAvailable(const void* data, size_t size) = 0;

 private:
  std::string m_file_path;
  std::unique_ptr<const std::uint8_t, std::function<void(const std::uint8_t*)> >
         m_data;
  size_t m_size;
};